1. Field of the Invention
The present invention pertains to a device for controlling the flow of intake air in a space heater. More specifically, the present invention pertains to a unitary airflow diffuser disposed at an input port of a combustion chamber of a portable, forced-air, space heater.
2. Related Background Art
Both gas fired (for example propane, butane and the like) and oil fired (for example fuel oil, kerosene, gasoline, and the like) portable, forced-air, space heaters are well known for use in otherwise unheated areas, such as construction sites, farm buildings, garages, work sheds, and outdoor recreation areas. U.S. Pat. No. 3,101,193 discloses one such oil fired portable space heater. Generally, oil fired space heaters include at least a fuel tank, a combustion chamber, a motor for driving a compressor and a fan, a nozzle assembly, and an igniter. Air supplied by the compressor is delivered to a chamber in the nozzle assembly. The compressed air in the chamber creates suction on the fuel line, which runs from the chamber to the fuel tank. The suction draws fuel from the fuel tank into the chamber and entrains, atomizes, and vaporizes the fuel with the compressed air. The nozzle assembly delivers the entrained, atomized, and vaporized fuel through a small borehole in a nozzle into one end, i.e., the input port, of the combustion chamber in the vicinity of the igniter, which may be a spark plug. The fan provides secondary combustion air and also serves to discharge the heated air through an opposite end, i.e., the discharge port, of the combustion chamber.
Efforts have been made to increase the efficiency, safety, and performance of space heaters by controlling the air-fuel mixture and otherwise affecting the combustion of the fuel within the combustion chamber. However, such efforts oftentimes are costly to implement making them commercially unacceptable.
One known approach for improving the efficiency, safety, and performance of space heaters is to control the airflow from the fan, which is directed toward, into, and within the combustion chamber. The objectives of this approach are to achieve more complete combustion, increase efficiency, and avoid the impingement of any unburned fuel and the flame on the interior surfaces of the heater. U.S. Pat. No. 3,129,748 discloses a multicomponent burner assembly for use in a space heater. The burner assembly comprises a burner body capped at its operating face by an annular control plate. A plurality of recesses in the burner body and a series of guides or deflector blades mounted on the inner face of the control plate are provided to control the airflow within the space heater to affect fuel ignition and combustion.
U.S. Pat. No. 3,706,446 provides another example of a multicomponent burner assembly including a burner head and a flame retention head. Further, U.S. Pat. No. 4,201,544 discusses a burner head with a plurality of curved fingers for deflecting air. The burner head shown in the '544 patent is discussed in more detail in U.S. Pat. No. 3,298,148.
One disadvantage of arrangements which employ one-piece burner heads, such as those shown in the foregoing patents, is that the burner head is generally fabricated using casting methods. See for example, U.S. Pat. No. 3,494,599. Casting results in increased manufacturing costs and production time.
Another arrangement for controlling airflow at the input of and within the combustion chamber is to provide a plate with a plurality of separate fins or vanes projecting therefrom at the input port of the combustion chamber. U.S. Pat. Nos. 4,532,914 and 4,081,238 are illustrative of such arrangements, in propane and kerosene fired forced-air space heaters, respectively. Although these arrangements avoid the need for a cast burner head, they suffer the disadvantage that the plate and the fins and vanes must be separately and individually fabricated. An additional disadvantage is that the fins and vanes must be separately and individually secured to the plate by means of rivets or the like. Such disadvantages increase manufacturing costs and production assembly time.
Gas, such as propane fired forced-air space heaters also are known. These heaters generally are simpler in certain aspects than oil fired space heaters as will be discussed below. Nevertheless, there is a need to combine the airflow into and through the combustion chamber of propane forced-air space heaters to optimize combustion.
Therefore, there is a need in the art for mechanisms that produce the desired airflow characteristics in the combustion chamber, which can be formed without resort to casting or other expensive manufacturing techniques, and that are suitable for use in oil and gas fired forced-air space heaters.
There is a further need in the art for such a mechanism for producing desired airflow characteristics, which is formed as a unitary piece, further reducing manufacturing costs of production assembly time of forced-air space heaters.